Catalytic cracking of hydrocarbons

ABSTRACT

Non-hydrogenative endothermic catalytic cracking of hydrocarbon, particularly petroleum, fractions at relatively low pressures and high temperatures in a system where the endothermic heat required for cracking is supplied by catalyst as the heat transfer medium, which catalyst has been heated by burning coke deposited on the catalyst during cracking; and wherein a decomposable compound of platinum, palladium, ruthenium, iridium, osmium, rhodium or rhenium, is introduced into contact with the cracking catalyst during said process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 659,308 filedFeb. 19, 1976, now U.S. Pat. No. 4,088,568 which in turn is acontinuation-in-part application Ser. No. 649,261 filed Jan. 15, 1976,now U.S. Pat. No. 4,072,600, which in turn is a continuation-in-part ofof application Ser. No. 440,890 filed Feb. 8, 1974 now abandoned whichis in turn a continuation-in-part of application Ser. No. 399,008 filedSept. 20, 1973, now abandoned; and a continuation-in-part of applicationSer. No. 599,920 filed July 28, 1975, now abandoned. The contents ofthese applications as well as the content of any patents and/orapplications referred to therein are hereby incorporated herein byreference.

BACKGROUND OF THE INVENTION

This invention relates to catalytic cracking of hydrocarbons. It moreparticularly refers to improvements in the endothermic catalyticcracking of petroleum fractions and alternating exothermic catalystregeneration.

Endothermic catalytic cracking of hydrocarbons, particularly petroleumfractions, to lower molecular weight desirable products is well known.This process is practiced industrially in a cycling mode whereinhydrocarbon feedstock is contacted with hot, active, solid particulatecatalyst without added hydrogen at rather low pressures of up to about50 psig and temperatures sufficient to support the desired cracking. Asthe hydrocarbon feed is cracked to lower molecular weight, more valuableand desirable products, "coke" is deposited on the catalyst particles.The coked catalyst is disengaged from the hydrocarbon products, whichare then resolved and separated into appropriate components. The cokedcatalyst particles, now cooled from the endothermic cracking anddisengaged from the hydrocarbon products, are then contacted with anoxygen containing gas whereupon coke is burned off the particles toregenerate their catalytic activity. During regeneration, the catalystparticles absorb the major portion of the heat generated by thecombustion of coke, i.e. they are "reflexively" heated, with consequentincrease of catalyst temperature. The heated, regenerated catalystparticles are then contacted with additional hydrocarbon feed and thecycle repeats itself.

A flue gas comprising carbon oxides is produced during regeneration. Inconventional operation this flue gas contains substantial quantities ofcarbon monoxide. The carbon monoxide is either vented to the atmospherewith the rest of the flue gas or is in some way burned to carbondioxide, in an incinerator or a CO boiler or the like.

It has recently become desirable to decrease the content of carbonmonoxide in the regenerator flue gas for at least two reasons. In thefirst place, CO combustion is extremely exothermic and in view of theincreasing cost of energy, burning CO in the regenerator increases theheat efficiency of the reflexive endothermic catalytic cracking system.In the second place, since carbon monoxide is an air pollutant, more andmore stringent controls are being placed upon its venting into theenvironment. It is therefore clearly desirable to provide means forburning carbon monoxide within a reflexive hydrocarbon catalyticcracking system. This has been attempted in the past and is beingattempted at present by means of increasing the temperature and airinput to the regenerator so as to support thermal combustion of carbonmonoxide in the regenerator. This technique has been difficult tocommercialize and to operate successfully in a smooth, steady statemanner.

In the past attempts have been made, in fact it has sometimes beencommercial practice, to employ special catalysts for this process whichcontain a cracking component and a component for catalyzing theoxidation of carbon monoxide. The CO oxidation components used in thepast have been metals of the transition element group and/or of the irongroup. In particular, manganese, cobalt and especially chromium havebeen used for this purpose.

Two major variants for endothermically cracking hydrocarbons are fluidcatalytic cracking (FCC) and moving bed catalytic cracking. In both ofthese processes as commercially practiced, the feed hydrocarbon and thecatalyst are passed through a "reactor"; are disengaged; the catalyst isregenerated with cocurrent and/or countercurrent air; and theregenerated reflexively heated catalyst recontacted with more feed tostart the cycle again. These two processes differ substantially in thesize of the catalyst particles utilized in each and also in theengineering of materials contact and transfer which is at leastpartially a function of the catalyst size.

In fluid catalytic cracking (FCC), the catalyst is a fine powder ofabout 10 to 200 microns, preferably about 70 micron, size. This finepowder is generally propelled upwardly through a riser reaction zonesuspended in and thoroughly mixed with hydrocarbon feed. The cokedcatalyst particles are separated from the cracked hydrocarbon products,and after purging are transferred into the regenerator where coke isburned to reactivate the catalyst. Regenerated catalyst generally flowsdownward from the regenerator to the base of the riser.

One typical example of industrially practiced moving bed hydrocarboncatalytic cracking is known as thermofor catalytic cracking (TCC). Inthis process the catalyst is in the shape of beads or pellets having anaverage particle size of about 1/64 to 1/4 inch, preferably about 1/8inch. Active, hot catalyst beads progress downwardly cocurrent with ahydrocarbon charge stock through a cracking reaction zone. In this zonehydrocarbon feed is endothermically cracked to lower molecular weighthydrocarbons while coke is deposited on the catalyst. At the lower endof the reaction zone the hydrocarbon products are separated from thecoked catalyst, and recovered. The coked catalyst is then passeddownwardly to a regeneration zone, into which air is fed such that partof the air passes upwardly countercurrent to the coked catalyst and partof the air passes downwardly cocurrent with partially regeneratedcatalyst. Two flue gases comprising carbon oxides are produced.Regenerated catalyst is disengaged from the flue gas and is then lifted,pneumatically or mechanically, back up to the top of the reaction zone.

The catalysts used in endothermic catalytic nonhydrogenative crackingare to be distinguished from catalysts used in exothermic catalytichydrocracking. Operating conditions also to be distinguished. While thecatalytic cracking processes to which this invention is directed operateat low pressures near atmospheric and in the absence of added hydrogen,hydrocracking is operated with added hydrogen at high pressures of up toabout 1000 to 3000 psig. Further, non-hydrogenative catalytic crackingis a reflexive process with catalyst cycling between cracking andregeneration (coke burn off) over a very short period of time, secondsor minutes. In hydrocracking, on the other hand, the catalyst remains incracking service for an extended period of time, months, betweenregeneration (coke burn off). Another important difference is in theproduct. Nonhydrogenative catalytic cracking produces a highlyunsaturated product with substantial quantities of olefins andaromatics, and a high octane gasoline fraction. Hydrocracking, incontrast produces an essentially olefin-free product with a relativelylow octane gasoline.

This invention is not directed to hydrocracking nor is it within thescope of this invention to use hydrocracking catalysts in the processhereof. Hydrocracking catalysts have an acidic cracking component, whichmay be a crystalline aluminosilicate zeolite, amorphous silica alumina,clays or the like, and a very strong hydrogenation/dehydrogenationcomponent. Strong hydrogenation/dehydrogenation components areillustrated by metals such as molybdenum, chromium and vanadium, andgroup VIII metals such as cobalt, nickel and palladium. These are usedin relatively large proportion, certainly large enough to support heavyhydrogenation of the charge stock under the conditions of hydrocracking.To the contrary, strong hydrogenation/dehydrogenation metals are neitherrequired nor desired as components of non-hydrogenative catalyticcracking. In fact, it is usual for some metals, such as nickel andvanadium, to deposit out on the catalyst from the charge stock duringnon-hydrogenative cracking. These are considered to be catalyst poisonsin this process and therefore to be avoided or at least minimized. Theirdetrimental effect in nonhydrogenative catalytic cracking is to increasethe coke and light gas, including hydrogen, produced in the crackingreaction and therefore to reduce the yield of desired liquid products,particularly gasoline.

FIG. 1 and the sectional element thereof shown in FIG. 2 arerepresentative of a commercial fluid catalytic cracking unit. Referringnow to FIG. 1, a hydrocarbon feed 2 such as a gas oil boiling from about600° F. up to 1000° F. is passed after preheating thereof to the bottomportion of riser 4 for admixture with hot regenerated catalystintroduced by standpipe 6 provided with flow control valve 8. Asuspension of catalyst in hydrocarbon vapors at a temperature of atleast about 950° F. but more usually at least 1000° F. is thus formed inthe lower portion of riser 4 for flow upwardly therethrough underhydrocarbon conversion conditions. The suspension initially formed inthe riser may be retained during flow through the riser for ahydrocarbon residence time in the range of 1 to 10 seconds.

The hydrocarbon vapor-catalyst suspension formed in the riser reactor ispassed upwardly through riser 4 under hydrocarbon conversion conditionsof at least 900° F. and more usually at least 1000° F. before dischargeinto one or more cyclonic separation zones about the riser discharge,represented by cyclone separator 14. There may be a plurality of suchcyclone separator combinations comprising first and second cyclonicseparation means attached to or spaced apart from the riser dischargefor separating catalyst particles from hydrocarbon vapors. Separatedhydrocarbon vapors are passed from separator 14 to a plenum chamber 16for withdrawal therefrom by conduit 18. These hydrocarbon vaporstogether with gasiform material separated by stripping gas as definedbelow are passed by conduit 18 to fractionation equipment not shown.Catalyst separated from hydrocarbon vapors in the cyclonic separationmeans is passed by diplegs represented by dipleg 20 to a dense fluid bedof separated catalyst 22 retained about an upper portion of riserconversion zone 4. Catalyst bed 22 is maintained as a downwardly movingfluid bed of catalyst countercurrent to rising gasiform material. Thecatalyst passes downwardly through a stripping zone 24 immediatelytherebelow and counter-current to rising stripping gas introduced to alower portion thereof by conduit 26. Baffles 28 are provided in thestripping zone to improve the stripping operation.

The catalyst is maintained in stripping zone 24 for a period of timesufficient to effect a higher temperature desorption of feed depositedcompounds which are then carried overhead by the stripping gas. Thestripping gas with desorbed hydrocarbons pass through one or morecyclonic separating means 32 wherein entrained catalyst fines areseparated and returned to the catalyst bed 22 by dipleg 34. Thehydrocarbon conversion zone comprising riser 4 may terminate in an upperenlarged portion of the catalyst collecting vessel with the commonlyknown bird cage discharge device or an open end "T" connection may befastened to the riser discharge which is not directly connected to thecyclonic catalyst separation means. The cyclonic separation means may bespaced apart from the riser discharge so that an initial catalystseparation is effected by a change in velocity and direction of thedischarged suspension so that vapors less encumbered with catalyst finesmay then pass through one or more cyclonic separation means beforepassing to a product separation step. In any of these arrangements,gasiform materials comprising stripping gas hydrocarbon vapors anddesorbed sulfur compounds are passed from the cyclonic separation meansrepresented by separator 32 to a plenum chamber 16 for removal withhydrocarbon products of the cracking operation by conduit 18. Gasiformmaterial comprising hydrocarbon vapors is passed by conduit 18 to aproduct fractionation step not shown. Hot stripped catalyst at anelevated temperature is withdrawn from a lower portion of the strippingzone by conduit 36 for transfer to a fluid bed of catalyst beingregenerated in a catalyst regeneration zone. Flow control valve 38 isprovided in transfer conduit 36.

This type of catalyst regeneration operation is referred to as a swirltype of catalyst regeneration due to the fact that the catalyst bedtends to rotate or circumferentially circulate about the vessel'svertical axis and this motion is promoted by the tangential spentcatalyst inlet to the circulating catalyst bed. Thus, the tangentiallyintroduced catalyst at an elevated temperature is further mixed with hotregenerated catalyst or catalyst undergoing regeneration at an elevatedtemperature and is caused to move in a circular or swirl pattern aboutthe regenerator's vertical axis as it also moves generally downward to acatalyst withdrawal funnel 40 (sometimes called the "bathtub") adjacentthe regeneration gas distributor grid. In this catalyst regenerationenvironment, it has been found that the regeneration gases comprisingflue gas products of carbonaceous material combustion tend to movegenerally vertically upwardly through the generally horizontally movingcirculating catalyst to cyclone separators positioned above the bed ofcatalyst in any given vertical segment. As shown by FIG. 2, the catalysttangentially introduced to the regenerator by conduit 36 causes thecatalyst to circulate in a clockwise direction in this specificembodiment. As the bed of catalyst continues its circular motion somecatalyst particles move from an upper portion of the mass of catalystparticles suspended in regeneration gas downwardly therethrough to acatalyst withdrawal funnel 40 in a segment of the vessel adjacent to thecatalyst inlet segment. In the regeneration zone 42 housing a mass ofthe circulating suspended catalyst particles 44 in upflowing oxygencontaining regeneration gas introduced to the lower portion thereof byconduit distributor means 46, the density of the mass of suspendedcatalyst particles may be varied by the volume of regeneration gas usedin any given segment or segments of the distributor grid. Generallyspeaking, the circulating suspended mass of catalyst particles 44undergoing regeneration with oxygen containing gas to removecarbonaceous deposits by burning will be retained as a suspended mass ofswirling catalyst particles varying in density in the direction ofcatalyst flow and a much less dense phase of suspended catalystparticles 48 will exist thereabove to an upper portion of theregeneration zone. Under carefully selected relatively low regenerationgas velocity conditions, a rather distinct line of demarcation may bemade to exist between a dense fluid bed of suspended catalyst particlesand a more dispersed suspended phase (dilute phase) of catalystthereabove. However, as the regeneration gas velocity conditions areincreased there is less of a demarcation line and the suspended catalystpasses through regions of catalyst particle density generally less thanabout 30 lbs. per cu. ft. A lower catalyst bed density of at least 20lb/cu. ft. is preferred.

A segmented regeneration gas distributor grid 50 positioned in the lowercross-sectional area of the regeneration vessel 42 is provided as shownin FIG. 1 and is adapted to control the flow of regeneration gas passedto any given vertical segment of the catalyst bed thereabove. In thisarrangement, it has been found that even with the generally horizontallycirculating mass of catalyst, the flow of regeneration gas is generallyvertically upwardly through the mass of catalyst particles so thatregeneration gas introduced to the catalyst bed by any given gridsegment or portion thereof may be controlled by grid openings madeavailable and the air flow rate thereto. Thus, oxygen containingcombustion gases after contact with catalyst in the regeneration zoneare separated from entrained catalyst particles by the cyclonic meansprovided and vertically spaced thereabove. The cyclone combinationsdiagrammatically represented in FIG. 1 are intended to correspond tothat represented in FIG. 2. Catalyst particles separated from the fluegases passing through the cyclones are turned to the mass of catalysttherebelow by the plurality of provided catalyst diplegs.

As mentioned above, regenerated catalyst withdrawn by funnel 40 isconveyed by standpipe 6 to the hydrocarbon conversion riser 4.

The regenerator system shown in FIGS. 1 and 2 is usually designed forproducing a flue gas that contains a substantial concentration of carbonmonoxide along with carbon dioxide. In fact, a typical CO₂ /CO ratio isabout 1.2.

As noted above, there has recently been a marked increase in the desireto reduce carbon monoxide emissions from the regenerator of a reflexivenon-hydrogenative catalytic cracking process. Prior proposed solutions,of increasing the temperature of the regenerator sufficient to thermallyburn CO, or of incorporating chromium or iron with the cracking catalystto support catalytic CO combustion, have not accomplished a sufficientreduction in CO emissions or, when this reduction has approachedsufficiency, it has been at the expense of a great detriment to theoperation and product distribution of the cracking reaction side of theprocess. In addition to the fact that increased production of coke onthe cracking side throws this entire reflexive system into heatimbalance, the increased production of light gas unduly strains thecapacity of the compressors and the entire gas plant, that is the seriesof separation operation in which the C₄ ⁻ gasiform part of the productis resolved into its component parts.

It is therefore an important object of this invention to provide a novelmeans of reducing carbon monoxide emissions from a reflexive,non-hydrogenative catalytic cracking process.

It is another object of this invention to provide a novel catalyst forsuch a process.

It is another object of this invention to provide an improved processfor the fluid catalytic cracking of gas oils in the absence of addedhydrogen.

Other and additional objects of this invention will become apparent froma consideration of this entire specification including the claimshereof.

Various references which have been uncovered may bear upon the subjectmatter of this application. The following list is not suggested to beexhaustive or all inclusive. It does, however, identify those presentlyknown references which, in the opinion of counsel, seem to bear uponthis subject matter:

U.S. Pat. No. 3,660,310; Kluksdahl

U.S. Pat. No. 3,788,977; Dolbear

U.S. Pat. No. 3,364,136; Chen et al

U.S. Pat. No. 2,436,927; Kassel

U.S. Pat. No. 3,226,339; Frilette et al

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 exemplifies a fluid catalytic cracking apparatus

FIG. 2 illustrates a swirl regenerator

FIG. 3 shows the relative oxidation activity of promoter metals

DETAILED DESCRIPTION OF THE INVENTION

In accord with and fulfilling these objects, one aspect of thisinvention resides in a novel catalyst comprising an acidic crackingcomponent and a minute quantity of one platinum group metal selectedfrom platinum, palladium, iridium, osmium, rhodium, ruthenium andrhenium. For convenience, these metals including rhenium shall behereinafter referred to as "a platinum group metal" even though it isknown that rhenium is not so located in the Periodic Table of Elementsas to usually qualify for this appellation. The platinum group metal maybe initially provided in a reduced or oxidized form of any givenvalence. In use it will equilibrate to such form and chemical nature asis induced by the reflexive cracking and regeneration system.

The platinum group metal may be a component of all catalyst particles oronly of some of the catalyst particles. In terms of its concentration inthe entire system, it must be present in a large enough proportion to beable to effect the reaction of carbon monoxide with oxygen to carbondioxide, provided the conditions in the regenerator are otherwisesufficient to support this combustion; e.g., sufficiently hightemperature and sufficient air. Yet it must not be present in aproportion so large that it substantially adversely affects theoperation of the cracking side of the process. This latter, upper limiton platinum group metal content is to some extent a reflection of thedesign capacity of the cracking system including auxiliaries anddownstream product resolution facilities compared to actual operatingthroughput. The upper level of platinum group metal content must be lessthan that which would cause this design capacity to be exceeded.

Further, as a practical consideration each of the seven metals of theplatinum group as defined herein has a different degree of effectivenessfor their intended use in this system. Therefore, numerical upper andlower limits of metal proportions are blanketing numbers for the entiregroup. They are not necessarily applicable as a proper range for anygiven species within this genus. Thus, for example, an appropriate upperlimit for the proportion of metal of the entire platinum group metalgenus is about 100 parts per million based upon the finished catalystformulation. While it is clear that this is a proper upper limit for thegenus, it is also clear that this numerical value may be quite high forcertain species of the genus, notably platinum and iridium in which casea preferred upper limit might better be set at about 10 parts permillion on the same basis.

It is also clear that although a lower numerical limit can be applied tothe proportion of "platinum group metal" used in this catalyst, thisvalue must also be considered as applied to the genus and should becarefully reconsidered as to each individual species. Thus, a lowerlimit of about 0.1 part per million of platinum group metal isconsidered to be appropriate with respect to the use of some metals,such as platinum, but this value may be lower than the minimum suitablefor the application of other metals such as rhenium for example.

In any case, however, the most appropriate measure of the amount of anyparticular platinum group metal is related exclusively to how itperforms in reflexive, endothermic, non-hydrogenative catalyticcracking. There should be a sufficient quantity to support as muchcombustion of carbon monoxide as is desired considering the inherentlimitations of any given operating system, such as temperaturelimitations based upon equipment metallurgy and/or coke producingpropensities of a particular feed or feed slate.

In this regard it is important to note that in some instances it may bedesirable to cause substantially all of the carbon burned in theregenerator to be oxidized all the way to carbon dioxide. In otherinstances, it may be desirable to cause only part of the carbon to beoxidized all the way to carbon dioxide and permit some substantialamount to be only partially oxidized to carbon monoxide. The use of theinstant catalyst now permits the refiner to select the exact amount ofheat to be generated in the regenerator as a function of efficientcarbon monoxide burning. It permits him to increase the regeneratortemperature by burning some of the carbon monoxide therein, (therebyreducing residual coke on regenerated catalyst and increasing theactivity of regenerated catalyst) and burning the rest outside theregenerator, for example in a steam generating CO boiler.

As noted, the novel catalyst of this invention can be used by itself ina reflexive catalytic cracking operation or it can be used in admixturewith otherwise conventional cracking catalyst. In either of these modes,the proportion of platinum group metal can be varied within thefunctional limits set forth above. It should be noted that it may bedesirable to vary the proportion of platinum group metal with time onstream, that is it may be desirable to modify an existing operatingreflexive cracking system which is utilizing a catalyst not employing aplatinum group metal by providing initial makeup fresh catalystcontaining relatively large proportions of platinum group metal, e.g.about 1 to 50 parts per million based upon total catalyst, and then toadd further quantities of makeup fresh cracking catalyst containingdecreasing proportions of platinum group metal until the accumulatedactive platinum metal content of the total catalyst inventory reachesthe desired level, e.g., about 0.05 to 5 parts per million based uponthe total catalyst inventory.

Since the amount of platinum group metal employed is so very small, itis extremely difficult to analyze the form of the metal on the catalystin operation, particularly after it has been on stream for awhile andhas gone through many cycles of cracking and regeneration.

The metal may be applied to the cracking catalyst after such has beenperformed. It may be incorporated during manufacture of the crackingcatalyst. It may be applied to a non-cracking substrate and this thenincorporated with a cracking catalyst, perhaps with a binder.

The platinum group metal may be present with the cracking catalyst asthe metal, oxide, sulfide, halide, sulfate, carbide, etc. The catalystcomposition may have, as a component thereof, a substrate or binder suchas silica, alumina, zirconia, magnesia, clay, mixtures thereof and/oramorphous or crystalline compounds thereof with each other or with othermaterials such as titania-zirconia. The cracking component may be anamorphous silica-alumina, an acid clay, an acid crystallinealuminosilicate zeolite particularly one of very low alkali, e.g.sodium, content and/or other known materials.

If the platinum group metal is incorporated with the cracking componentoutside the cracking/regeneration system, such may be by impregnation,ion exchange, vapor deposition or otherwise, by contacting a preformedcracking catalyst composition or one or more components thereof with asolution of a compound of the metal in an appropriate amount necessaryto provide the desired minute concentration of metal needed for thisinvention. The platinum group metal may be incorporated during any stepin the catalyst preparation as well as with the unfinished catalyst.Specific examples of suitable platinum group metal compounds include themetal halides, preferably chlorides, nitrates, ammine halides, oxides,sulfates, phosphates and other water-soluble inorganic salts; also asmetal carboxylates of from 1 to 5 carbon atoms; or as alcoholates.Specific examples include palladium chloride, chloroplatinic acid,ruthenium penta-ammine chloride, osmium chloride perrhenic acid,dioxobis(ethylenediamine)rhenium(V) chloride, rhodium chloride and thelike.

The platinum group metal may be incorporated with the cracking componentwhen the latter is contained in the cracking/regeneration system. Themetal may be added into the reflexive endothermic cracking/regenerationsystem as an emulsion, suspension or solution in the oil feed, forexample. The metal, i.e. Pt, Pd, Ru, Ir, Os, Rh or Re may be in any oneof a large number of metallic or non-metallic forms collectivelydescribed herein as "decomposable." Included as decomposable metalcompounds, for example, are: suspensions of colloidal platinum;dispersions of platinum on an inorganic base such as alumina, such basehaving a particle size substantially smaller, i.e. less than about half,than the average particle size of the catalyst, such as colloidalalumina; suspensions of the aforesaid dispersions in a fluid carriersuch as fuel oil, air or water; emulsions of aqueous solutions ofplatinum compounds; and vapors of the volatile metal compounds in asuitable carrier such as an inert gas. Thus, the term "decomposable" asused herein broadly encompasses all forms of the metal suitable forincorporation into and in association with the cracking component,whether or not the said cracking component is contained within thecracking/regeneration system. In general, the decomposable metalcompound, on contact with the cracking component in thecracking/regeneration system, undergoes transformation such that anintimate, irreversible association is formed with the crackingcomponent, i.e. the decomposable metal compound loses its identity andcannot readily be recovered as such by ordinary physical means ofseparation.

The decomposable metal compounds that may be introduced directly intothe unit, i.e. the cracking/regeneration system, include thesehereinabove mentioned, by way of example, alternatively, an oil-solubleor oil-dispersible compound of the metal may be added in suitable amountof a hydrocarbon feedstock, such as a gas oil charge stock, forincorporation in the catalyst as the charge is cracked. Such compoundsinclude metal diketonates, carbonyls, metallocenes, olefin complexes of2 to 20 carbons, acetylene complexes, alkyl or aryl phosphine complexesand carboxylates of 1 to 20 carbons. Specific examples of these areplatinum acetylacetonate, tris (acetylacetonato) rhodium (III),triiodoiridium (III) tricarbonyl, π-cyclopentadienylrhenium (I)tricarbonyl, ruthenocene, π-cyclopentadienylosmium (I) dicarbonyl dimer,dichloro (ethylene) palladium (II) dimer, (π-cyclopentadienyl)(ethylene) rhodium (I), diphenylacetylenebis (triphenylphosphino)platinum (O), bromomethylbis (triethylphosphino) palladium (II),tetrakis (triphenylphosphino) palladium (O),chlorocarbonylbis(triphenylphosphino) iridium (I), palladium acetate,and palladium naphthenate.

The feedstocks which may be cracked using the catalysts of thisinvention include any conventional hydrocarbon stocks, such as naphthas,gas oil, light and heavy distillates, residual oils and the like.

There are several other ways to introduce the above-describeddecomposable metal compounds into the unit other than with the oil feed.Referring now to FIG. 1, by way of illustration for an FCC unit, thedecomposable metal compound may be introduced suspended in the air feed46 to the regenerator; or with the steam introduced to the strippingsection of the reactor via 26; or directly into spent catalyst transferconduit 36; or into regenerated catalyst standpipe 6; or into densefluid bed 22; or into the upper portion of riser conversion zone 4; orinto cyclone separating means 32; or dipleg 34; or into catalyst bed 44;or into suspended catalyst particles 48; or into separating means suchas diplegs 60, 62, 64 and 66 contained within housing 42. Directinjection into the dense bed of the regenerator 44 is a preferred meansof introduction.

Whereas optional methods for introducing a decomposable metal compoundhave been illustrated for an FCC (fluid catalytic cracking) unit, movingbed systems likewise provide numerous locations for injection. Also, ifthe "swirl" regenerator of FIG. 1 is replaced with a riser-regenerator,more fully described hereinafter, the decomposable metal compound may beintroduced into the riser itself, the dense bed of regenerated catalyst,or into the conduit for recycle of regenerated catalyst to spentcatalyst, as well as into other locations of the apparatus equivalent tothose described for FIG. 1.

The minute quantities of the metal compound catalysts used in thisinvention affect the overall catalytic cracking process to a differentextent and in a different manner than prior catalysts used by thepetroleum industry in attempts to burn CO in the regenerator. They alsocause different results as compared with non-catalytic CO-burning.Nickel and vanadium are both known to be deposited on cracking catalystfrom the hydrocarbon feed and both are known to be carbon monoxideoxidation catalysts. Yet these materials are considered by the petroleumindustry to be catalyst poisons. To understand this, one must considerthat the aim of catalytic cracking is increased production of gasolineand other lower boiling distillate fractions from whole crude oil.

When a catalyst component, such as nickel or vanadium, is considered tobe a poison even though it has some activity for accomplishing adesirable objective, e.g. catalyzing CO oxidation, it is because itsoverall effect is to reduce the gasoline yield from the entire system.In the case of nickel and vanadium, and perhaps to a lesser extent othertransition metals such as manganese and/or chromium, there is asignificant increase in the coke produced on the cracking side of areflexive catalytic cracking process as defined herein. This increasedcoke production may result in a higher residual carbon on regeneratedcatalyst in spite of the somewhat increased catalytic CO combustion.With higher residual carbon, the net effect of the deposition of thesemetals is to reduce the catalytic activity and gasoline selectivity ofthe cracking component. To the contrary, the miniscule amounts of thespecial CO oxidation catalyst components of the instant invention have anet effect of reducing the equilibrium coke levels on the crackingcatalyst. These novel catalysts also have the net effect of increasinggasoline selectivity.

Consideration of thermal (non-catalytic) CO oxidation shows thatinitiating and sustaining non-catalytic CO oxidation requires andproduces much higher temperatures than in the presence of a catalyst. Itwould appear that zeolite cracking catalyst may be adversely affected byexposure to high temperatures, such as those encountered in thermal(non-catalytic) CO burning. Therefore, the net effect of non-catalyticCO burning in the regenerator of a reflexive non-hydrogenative crackingsystem may be to decrease gasoline production.

In conventional reflexive, non-hydrogenative, endothermic catalyticcracking of hydrocarbons coupled with rapid cyclic regeneration (cokeburn-off) of catalyst, the regenerator operates in one of severalgeneral modes. In FCC type of operations one regenerator scheme,exemplified by FIG. 1, utilizes a dense fluidized bed of catalyst intowhich cooled, coked catalyst is fed from the cracking reaction zone andfrom which regenerated, heated catalyst is taken for transfer to thefeed inlet point of the cracking side reaction zone. It is usual for thedilute phase temperature in such regenerators to be higher, sometimes asmuch as 100° F. or more, than the dense bed temperature. The flue gasmay be at a still higher temperature. One marked advantage of using aplatinum group metal modified catalyst according to this invention, incombination with increasing the oxygen input to the regeneration zone,is that it tends to cause carbon monoxide to burn in the dense phaserather than in the dilute phase whereby reducing the temperaturedifferential (ΔT) between the two phases. The temperature of the dilutephase can be markedly reduced while the temperature of the dense phaseis only moderately increased. This permits the additional heat generatedby CO combustion to be invested in the catalyst being returned to thecracking zone to a greater extent.

There exist, in the market today, new designs for FCC units whichoperate with conventional catalysts and conversion of CO is accomplishedthermally rather than catalytically. However, there are many problems inactual operation of these units. These problems may be eliminatedthrough the use of the catalyst of this invention. With catalystscontaining suitable low concentrations, usually well under 10 ppm total,of one or more metals chosen from Pt, Pd, Rh, Ru, Ir, Os and Re, severaladvantages become apparent in the operations of these units. The ΔTvalues decrease; that is, the dense bed temperature increases and thereis a sharp decrease in the dilute phase, cyclone and effluent gastemperature. More process heat is thereby retained by the dense bed foruse in the reactor. With the increased dense bed temperature, a lowerrate of catalyst circulation is required to supply the same amount ofheat to the reactor. The reduced catalyst circulation results in lessattrition and lower particulate emissions with the effluent regenerationgas, and may also reduce catalyst makeup requirements to maintain agiven activity. With the higher dense bed temperature, the residualcarbon on the catalyst returning to the reactor is reduced. It has beenestablished that lower residual carbon will result in a higher effectivecatalyst activity. The lower catalyst circulation rate and the lowerresidual coke will improve selectivity, particularly by lowering yieldof coke based on charge and a corresponding increase on recoverableproducts. With the catalyst of this invention, steam injection to lowerhigh cyclone temperatures is unnecessary. Injection of torch oil toraise the temperature of the dense bed to sustain thermal conversion ofCO is also unnecessary. Aside from the cost of the steam and torch oil,both of these controls accelerate the deactivation of the catalyst andmake the process more difficult to control. A further advantage todecreased catalyst circulation rate is less erosion of the internals ofthe system. Although preheat of the feed to the cracking unit can alsoeffect or allow a reduction in catalyst circulation rate, the efficiencyof energy transfer in the form of heat to the reactor is greater whenthe heat is generated directly in the bed of catalyst.

In some fluid cracking units as well as in moving bed units,insufficient coke is deposited on the catalyst during the cracking cycleto generate enough heat when the coke is burned in the regenerator. Insuch cases, the temperature in the regenerator is too low to effectivelyreduce the residual carbon to a desirable level (e.g., below 0.2% wt.C). Furthermore, new, higher selectivity cracking catalysts, whichproduce more high-valued liquid products at the expense of coke, cannotbe used in these units, since they would be even more difficult toregenerate. With the catalyst of this invention sufficient additionalheat is generated by oxidation of carbon monoxide to take advantage ofany such improved selectivities.

Another type of FCC regeneration system utilizes a lower dense fluidizedbed of catalyst to which cooled, coked catalyst is added from thecracking zone and an upper dispersed or dilute phase into which all ofthe catalyst from the dense phase is projected. Some of the hotregenerated catalyst from the upper dilute phase may be recycled to thelower dense bed in order to keep the temperature of the dense bed hotenough to at least start coke combustion. In this configuration,substantially all of the regenerated catalyst returned to the crackingzone is taken from the upper dispersed phase and substantially nonecomes directly from the lower dense bed. The use of a platinum groupmetal modified cracking catalyst, together with sufficient oxygen feedto the regenerator to support carbon monoxide combustion, results inincreasing the dense bed temperature, decreasing the residual coke levelon the catalyst in the dense bed and decreasing or perhaps eveneliminating the need for hot catalyst recycle from the upper dilutephase to the lower dense phase.

In moving bed reflexive catalytic cracking exemplified by TCC referredto aove, the coked catalyst is transferred from a cracking zone to aregeneration zone which is sometimes called a kiln. The kiln itself hasan upper zone and a lower zone. Oxygen containing gas, preferably air,is fed between the zones while coked catalyst is fed to the topmost ofthe two zones. The air passes countercurrent to the coked catalyst inthe upper zone burning off some coke creating a flue gas comprisingcarbon oxides, including substantial quantities of carbon monoxide. Thepartially decoked catalyst from the upper zone now passes cocurrent to aportion of the fed air in the lower zone where further coke deposits areburned off creating a flue gas comprising carbon oxides. When a catalystincorporating a platinum group metal as set forth herein is used, andsufficient oxygen is introduced into the kiln, small changes areobserved in carbon dioxide to carbon monoxide ratio in the flue gas fromthe upper, countercurrent regeneration zone. Under these sameconditions, however, the flue gas from the lower, cocurrent regenerationzone is observed to retain substantially no carbon monoxide, it havingbeen substantially all oxidized to carbon dioxide. The regeneratedcatalyst leaving the kiln is substantially hotter than without theinstant platinum group metal modification and the total flue gas, whichis a composite of the upper and lower kiln zone flue gases, may havesomewhat less carbon monoxide.

According to one feature of this invention, a platinum group metal canbe incorporated with the cracking catalyst during manufacture thereof.In the alternative, a decomposable compound of a platinum group metalcan be brought into contact with the cracking catalyst during its use ina reflexive cracking process. For example in a TCC process adecomposable compound of a platinum group metal can be applied directlyto coked cracking catalyst between the cracking reaction zone and theregeneration kiln zone. This type of operation, coupled with feedingsufficient air, will cause at least some of the carbon monoxidegenerated by coke burning in the upper countercurrent regeneration zoneto be burned to carbon dioxide thereby at least reducing the carbonmonoxide content of the flue gas from the upper regeneration zone. Inthis regard it should be understood that there is substantialcompetition, particularly in the upper regeneration zone, between thecoke and the carbon monoxide, for the available oxygen. Therefore, inthe upper zone, where relatively low temperatures and high coke levelsprevail, it is difficult to burn CO with any high degree of efficiency.

Another aspect of this invention which tends to enable one to increasethe utility of the cracking catalyst hereof modified with the additionof minute quantities of platinum group metal, particularly in moving bedtype cracking, is to recycle some small amount of regenerated catalystfrom the kiln exit to the kiln inlet. Recycle proportions may be up toabout 10 weight percent or perhaps even more. It is appropriate to keepthis recycle down to a minimum since it increases the necessary catalystinventory. It is advantageous, however, in that it results in hotter andcleaner regenerated catalyst and in less carbon monoxide in the fluegas.

A further aspect of this invention, in conjunction with moving bed, e.g.TCC, cracking systems utilizing platinum group metal modified crackingcatalyst, involves a change in the conventional flue gas venting scheme.In conventional operation, the flue gas from the lower kiln is admixedwith the flue gas from the upper kiln and the mixture vented. Accordingto this aspect of this invention, the flue gas from the upper kiln,which contains substantial quantities of carbon monoxide, is fed intothe lower kiln regeneration zone along with the air feed thereto. Thispermits the carbon monoxide laden upper flue gas to contact partiallyand fully regenerated platinum group metal containing catalyst andexcess air and therefore permits and encourages carbon monoxide to beburned to carbon dioxide to a greater extent that has heretofore beenpossible.

It is conventional in moving bed catalytic cracking systems to operatethe entire cycle of cracking followed by regeneration with a continualdownward flow of catalyst, and then to pneumatically or mechanicallylift the regenerated catalyst from the bottom of the regenerator kiln tothe top of the cracking reactor. Some refiners use air in the pneumaticlift, some use a combination of steam and flue gas. With theincorporation of minute amounts of platinum group metal with thecracking catalyst an opportunity presents itself for substantiallyreducing, or perhaps even eliminating, carbon monoxide from the fluegas. According to this aspect of this invention, hot regeneratedcatalyst is lifted, as slowly as practical, with a mixture of flue gasand air. The platinum group metal on the hot regenerated crackingcatalyst will catalyze the combustion of carbon monoxide in the liftpipe. This will not only purify the vented flue gas, but it will alsofurther heat the regenerated catalyst so as to enable it to moreefficiently catalyze the hydrocarbon cracking reactions.

It is of course within the scope of the instant invention to use variouscombinations of two or more features as set forth herein. Alsocontemplated as within the scope of the present invention is to usecombinations of the recited metals, Pt, Pd, Ru, Ir, Os, Rh and Re.

The following examples illustrate certain aspects of the process of thisinvention, and are not to be construed as limiting thereon.

EXAMPLE 1

215 cc of an aqueous Pd (NO₃)₂ solution containing 0.0103 g. Pd/literwere added to 222 g, bone dry basis, of a calcined RENaY containing 16.1wt. % Re₂ O₃ and 2.7 wt. % Na to 0.001 wt.% (10 ppm) Pd. The zeolite wascalcined at 1200° F. for 1 hour. The zeolite (10 wt.%) was incorporatedin a matrix (90 wt.%) consisting of 40 wt.% Georgia kaolin, 57.4 wt.%SiO₂, 0.6 wt.% Al₂ O₃, and 2 wt.% ZrO₂ to provide 1 ppm palladium in thecomposite catalyst. The matrix was prepared by mixing water, kaolin,Q-Brand sodium silicate (28.9 wt.% SiO₂, 8.9 wt.% Na₂ O, and 62.2 wt.%H₂ O), aluminum sulfate, sodium zirconium sulfate, and sulfuric acid.The mixture was spray dried and the catalyst was exchanged with anaqueous 5 wt.% (NH₄)₂ SO₄ solution, washed, and impregnated with anaqueous 7 wt.% RECl₃.6H₂ O solution. The catalyst was then dried in anoven at about 250° F. and a portion of it was steamed for 4 hours at1400° F. and 0 psig, the heating to 1400° F. being carried out in a N₂atmosphere.

EXAMPLE 2

215 cc of an aqueous H₂ PtCl₆ solution containing 0.0103 g Pt/liter wereadded to another 222 g portion of the calcined RENaY of Example 1 toprovide 10 ppm platinum. A catalyst was then prepared by the sameprocedure as in Example 1.

The cracking performances of the catalysts of Examples 1 and 2 weredetermined. A wide-cut Mid-Continent gas oil feedstock was cracked at925° F. at a catalyst-to-oil ratio of 3 by wt. 8.3 WHSV, catalystresidence time 2.4 minutes; the results were:

    ______________________________________                                                         Ex.        Ex.                                               Catalyst (Example)                                                                             1          2        Blank*                                   ______________________________________                                        Conversion, % vol.                                                                             74.4       70.7     72.1                                     C.sub.5 + gasoline % vol.                                                                      65.0       63.0     64.3                                     Total C.sub.4 's, % vol.                                                                       14.4       12.6     13.3                                     Dry Gas, % wt.   6.4        5.6      5.6                                      Coke, % wt.      2.5        2.3      2.3                                      Carbon on Cat., % wt.                                                                          0.71       0.65     0.65                                     Hydrogen Factor**                                                                              39         27       30                                       ______________________________________                                         *Catalyst without added metal component.                                      **100 × [moles H.sub.2 /moles C.sub.1 + C.sub.2                    

The two catalysts were subjected to regeneration in two successivestages. The conditions of each stage of regeneration were as follows:Air was passed over the catalyst at a rate of 25 cc/min./gram ofcatalyst at 1000° F. and atmospheric pressure for 8 minutes, and the gaswas collected.

The results were as follows:

    ______________________________________                                        First Stage      Ex. 1      Ex. 2    Blank*                                   ______________________________________                                        CO.sub.2, mol %  3.5        5.2      4.0                                      CO, mol %        2.7        0        3.2                                      CO.sub.2 /CO     1.3        ∞  1.3                                      Initial Carbon, % wt.                                                                          0.71       0.65     --                                       Final Carbon, % wt.                                                                            0.42       0.43     --                                       ______________________________________                                        Second Stage     Ex. 1      Ex. 2    Blank*                                   ______________________________________                                        CO.sub.2, mol %  2.0        2.7      2.4                                      CO, mol %        1.2        0        1.7                                      CO.sub.2 /CO     1.7        ∞  1.4                                      Initial Carbon, % wt.                                                                          0.42       0.43     --                                       Final Carbon, % wt.                                                                            0.28       0.26     --                                       ______________________________________                                         *Catalyst without metal component                                        

EXAMPLE 3

An RENaY (222 g) was prepared in the same manner as in Example 1, exceptthat it was uncalcined. Thereafter, 163 cc of an aqueous H₂ PtCl₆solution containing 0.0137 g Pt/liter were added to provide 0.001 wt. %(10 ppm) platinum. A composite catalyst containing 1 ppm platinum wasthen prepared by the same procedure as in Example 1.

Cracking data, using the same feedstock as in the previous examples andunder the same conditions, and regeneration data under the sameconditions as in the previous examples were as follows:

    ______________________________________                                        Catalyst           Ex. 3       Blank                                          ______________________________________                                        Conversion, % vol. 76.2        74.4                                           Coke, % wt.        3.0         2.4                                            Carbon on Cat., % wt.                                                                            0.84        0.69                                           Hydrogen Factor    29          17                                             ______________________________________                                        Regeneration       Stage 1     Stage 1                                        ______________________________________                                        CO.sub.2, mol %    8.3         3.3                                            CO, mol %          0.6         3.0                                            CO.sub.2 /CO       13          1.1                                            Final C, % wt.     0.56        0.56                                           ______________________________________                                                           Stage 2     Stage 2                                        ______________________________________                                        CO.sub.2, mol %    4.7         1.6                                            CO, mol %          ≦0.1 1.4                                            CO.sub.2 /CO       ≧47  1.1                                            Final C, % wt.     0.44        --                                             ______________________________________                                    

The increased CO₂ /CO mole ratio with the presence of only 1 ppm ofplatinum clearly illustrates the advantage of the metal component in thecatalysts of this invention.

EXAMPLE 4

A rare-earth exchanged zeolite Y (15.8 wt. % RE₂ O₃, 2.7% Na) wasslurried with an aqueous solution containing [Pt(NH₃)₆ ]Cl₄. Theresulting platinum-containing zeolite was filtered, dried at 250° F.,and calcined at 1200° F. for one hour. The resulting zeolite wasincorporated in a matrix as described in Example 1 to give a finishedcracking catalyst containing 10% of the zeolite by weight to which 1 ppmplatinum had been added. A blank catalyst was prepared similarly, the[Pt(NH₃)₆ ]Cl₄ being eliminated from the zeolite slurry.

Both catalysts were heated to 1400° F. and steamed as in Example 1, usedto crack the feedstock of Example 1 and regenerated under the conditionsof Example 2. The results were as follows:

    ______________________________________                                                           Ex. 4       Blank                                          ______________________________________                                        Conversion, % vol. 76.1        73.9                                           Coke, % wt.        2.8         2.5                                            Carbon on Cat., % wt.                                                                            0.82        0.73                                           Hydrogen Factor    19          16                                             ______________________________________                                        Regeneration       Stage 1     Stage 1                                        ______________________________________                                        CO.sub.2, % mol    5.9         3.3                                            CO, % mol          0.15        1.7                                            CO.sub.2 /CO       39          1.9                                            ______________________________________                                    

EXAMPLE 5

A commercial cracking catalyst consisting of 15% REY and 85% matrix of57.4% silica, 0.6% alumina, 40% clay and 2.0% zirconia, which had beenspray dried, exchanged with ammonium nitrate and water-washed, wasslurried with an aqueous solution of rare earth chloride and Pt(NH₃)₄Cl₂ sufficient to provide 3% RE₂ O₃ and 2 ppm platinum to the finishedcatalyst. The catalyst was spray dried, heated in nitrogen, then steamedfor 4 hours at 1400° F. A blank catalyst without platinum was preparedand treated similarly, Pt (NH₃)₄ Cl₂ being omitted from the slurry.

Both catalysts were used to crack the same feedstock as in Example 2 andregenerated under the conditions of Example 2. The results were asfollows:

    ______________________________________                                                           Ex. 5       Blank                                          ______________________________________                                        Conversion, % vol. 79.5        78.8                                           Coke, % wt.        3.3         3.1                                            Carbon on Cat., % wt.                                                                            0.945       0.884                                          Hydrogen Factor    15.8        12.1                                           ______________________________________                                        Regeneration       Stage 1     Stage 1                                        ______________________________________                                        CO.sub.2, mol %    8.2         4.2                                            CO, mol %          1.2         3.4                                            CO.sub.2 /CO       6.8         1.2                                            ______________________________________                                                           Stage 2                                                    ______________________________________                                        CO.sub.2, mol %    5.7                                                        CO, mol %          0.25                                                       CO.sub.2 /CO       23                                                         ______________________________________                                    

EXAMPLE 6

A number of metals of the platinum group and rhenium were used to treata catalyst containing 15% REY silica-alumina-clay-zirconia matrix(similar to that of Example 5). Solutions of the metal salts ofappropriate concentration were added to the catalyst until it was wet.The finished catalyst was dried at 250° F. for 24 hours, heated innitrogen at 1400° F. over 31/2 hours and steamed for 4 hours. The metalsalts were the chlorides of iridium, osmium and rhodium, and [Ru(NH₃)₅Cl₂ ]Cl₂ rhenium di(ethylene diamine) dioxide chloride, Pt(NH₃)₄ Cl₂ andPd(NO₃)₂. A total amount of metal equal to 3 ppm was so supplied. Afterthe cracking of a wide-cut Mid-Continent gas oil feed and regenerationstudies as in Example 2, the following results were obtained.

    __________________________________________________________________________    Regeneration                                                                  Stage 1                                                                              Blank                                                                             Pt Ir Os Pd Rh Ru Re Pt + Re*                                      __________________________________________________________________________    CO.sub.2, % mol                                                                      3.8 7.1                                                                              5.7                                                                              4.2                                                                              4.6                                                                              4.9                                                                              4.5                                                                              3.8                                                                              4.6                                           CO, % mol                                                                            3.7 0.15                                                                             0.3                                                                              2.8                                                                              1.15                                                                             1.2                                                                              2.8                                                                              3.5                                                                              3.1                                           CO.sub.2 /CO                                                                         1.0 47 19 1.5                                                                              4.0                                                                              4.0                                                                              1.6                                                                              1.1                                                                              1.5                                           __________________________________________________________________________    Stage 2                                                                              Blank                                                                             Pt Ir Os Pd Rh Ru Re Pt + Re*                                      __________________________________________________________________________    CO.sub.2, % mol                                                                      --  -- -- 2.0                                                                              -- 2.7                                                                              3.5                                                                              2.7                                                                              --                                            CO, % mol                                                                            --  -- -- 1.65                                                                             -- 0.7                                                                              1.0                                                                              1.4                                                                              --                                            CO.sub.2 /CO                                                                         --  -- -- 1.2                                                                              -- 3.9                                                                              3.5                                                                              1.9                                                                              --                                            __________________________________________________________________________     *Made from H.sub.2 PtCl.sub.6 and HReO.sub.4 to provide 1.5 ppm of each       metal.                                                                   

EXAMPLE 7

In this example, equilibrium catalyst withdrawn from a commercial FCCunit was used. A wide-cut Mid-Continent gas oil stock was cracked at929° F., 3 catalyst-oil ratio ratio, 2.4 minute catalyst residence time.The catalyst was regenerated in place in 2 stages under the conditionsof Example II. Then, the same gas oil, but now containing platinumacetylacetonate dissolved therein in sufficient quantity to provide 1ppm platinum on the catalyst, was introduced into the cracker at thesame conditions, except slightly higher temperature. The catalyst wasregenerated again. Then the platinum-containing feed was again crackedover the same catalyst, and again the catalyst was regenerated. Thefollowing results were obtained:

    ______________________________________                                                                  Gas Oil   Gas Oil                                   Cracking Feed   Gas Oil   & Pt      & Pt                                      ______________________________________                                        Cycle           1         2         3                                         Temperature, ° F.                                                                      929       936       926                                       Conversion, % vol.                                                                            56.5      57.3      50.4                                      Coke, % Wt.     2.3       2.4       2.3                                       Carbon on Cat., % wt.                                                                         0.67      0.67      0.67                                      Hydrogen Factor 25        29        31                                        ______________________________________                                        Regeneration    Stage 1                                                       ______________________________________                                        CO.sub.2, % mol 3.2       5.1       5.6                                       CO, % mol       2.7       0.18      0.10                                      CO.sub.2 /CO    1.2       28        56                                        Estimated Pt on Catalyst                                                      at end of Cycle, ppm                                                                          0         1         2                                         ______________________________________                                    

EXAMPLE 8

A commercial amorphous silica-alumina fluid cracking catalyst consistingof 13% Al₂ O₃, 87% SiO₂ was impregnated with an aqueous solution of Pt(NH₃)₄ Cl₂, oven-dried at 250° F., then heated and steamed at 1400° F.as in Example 1. The amount of platinum compound supplied was equivalentto 3 ppm of the metal. The catalyst without metal addition (blank),similarly treated, and the platinum-containing catalyst were used in thefluid cracking of the Mid-Continent gas oil stock, and then regeneratedunder the conditions of Example 2. The results were as follows:

    ______________________________________                                        Catalyst            Ex. 8     Blank                                           ______________________________________                                        Conversion, % vol.  35.8      35.6                                            Coke, % wt.         1.82      1.54                                            Carbon on Cat., % wt.                                                                             0.52      0.44                                            ______________________________________                                        Regeneration        Stage 1                                                   ______________________________________                                        CO.sub.2, % mol     4.8       2.2                                             CO, % mol           ≦0.05                                                                            1.2                                             CO.sub.2 /CO        ≧96                                                                              1.8                                             ______________________________________                                    

EXAMPLE 9

Moving bed catalysts are also improved by the presence of the addedmetal component of this invention. (a) A blank catalyst was prepared byincorporating 7.5% of the calcined rare-earth exchanged zeolite Y ofExample 4 and 40% alumina fines in a silica-alumina matrix (93.6% SiO₂,6.4% Al₂ O₃) by the bead technique described in U.S. Pat. No. 3,140,249.After base-exchange and washing, the hydrogel beads were dried in puresteam of atmospheric pressure at 270° F. for 15 minutes, then at 340° F.for 15 minutes. The dried catalyst was finished by a 14-hour steamtreatment at 1290° F. with 100% steam at atmospheric pressure. Thisblank catalyst was used in static bed cracking of a Mid-Continent gasoil at 875° F., a liquid hourly space velocity of 3 and a catalyst/oilratio of 2 with 10 minutes on stream. The spent catalyst was regeneratedand the CO₂ /CO ratio determined. (b) Rare-earth exchanged zeolite Yfilter cake, 1530.6 g, containing 49.0%=750 g of solids, was mulled with160 cc of a H₂ PtCl₆ solution containing 10.03 mg of Pt until uniform,then dried at 250° F. and calcined at 1200° F. for 3 hours. The productcontained 13.4 ppm of platinum designed to provide 1 ppm of platinum tothe catalyst after combination with the matrix. The preparation of thecatalyst was completed as above. (c) The blank zeolite-matrix beadhydrogel was treated for 1 hour with sufficient Pt(Nh₃)₄ Cl₂ solution tosupply 1 ppm of platinum based on the finished catalyst. (d) Thecalcined zeolite of paragraph (a) was used to prepare a catalyst similarto that described in (a) except that the matrix contained about 2200 ppmof cogelled Cr₂ O₃.

These catalysts were also used in cracking the said feedstock at thesame conditions, and were regenerated at the conditions of Example 2.The following results were obtained:

    ______________________________________                                        Catalyst        (a)     (b)     (c)   (d)                                     ______________________________________                                        Conversion, % vol.                                                                            68.8    69.3    70.4  70.9                                    Coke, % wt.     2.9     3.2     3.1   3.2                                     ______________________________________                                        Regeneration                                                                  ______________________________________                                        CO.sub.2, % mol 5.5     7.3     8.3   5.4                                     CO, % mol       4.8     0.4     0.2   5.0                                     CO.sub.2 /CO    1.1     18      42    1.1                                     ______________________________________                                    

EXAMPLE 10

A commercial clay-derived alumino-silicate zeolite cracking catalyst,containing about 55% by weight of alumina and about 45% by weight ofsilica and having an average particle size of between 58 and 64 microns,was employed in this example. A 1000 gram sample was mixed with 3500 ccof a solution containing 58.4 grams of RECl₃.6H₂ O and 2.7 mg of Pt asplatinum tris (ethylene diamine) tetrachloride. After stirring for 30minutes at 75° C. the catalyst was filtered out, water-washed and driedat 250° F. The catalyst contained 3 ppm platinum and 3% by weight ofrare earth oxide. Another sample of the same clay-derived catalyst("Blank") was treated similarly, but without the platinum although witha slightly higher rare earth concentration present in the solution. Thefinal catalyst contained 4.2% by weight of rare earth oxide. Bothcatalysts were steamed and tested for cracking performance as in Example2.

A portion of each coked catalyst from the test was blended with uncokedsteamed catalyst so that the carbon level of the mixture was 0.65% byweight. Regeneration was conducted at 1340° F. and atmosphericpressuring using 1.38 moles of oxygen per mole of carbon and the gas wascollected. The following data were obtained:

    ______________________________________                                        Regeneration       Ex. 10     Blank                                           ______________________________________                                        CO.sub.2, % mol    9.1        7.6                                             CO, % mol          0.3        3.6                                             CO.sub.2 /CO       30         2.1                                             ______________________________________                                    

EXAMPLE 11

The catalyst of Example 4, containing 1 ppm of platinum was calcined at1200° F. in N₂ for 3 hours. A wide-cut Mid-Continent gas oil feedstockwas cracked over this catalyst at 910° F. at a catalyst to oil ratio of2.0 by weight, 12.5 WHSV and catalyst residence time of 2.4 minutes.

The coked catalyst from this run was blended in various concentrationswith an equilibrium commercial zeolite catalyst withdrawn from acommercial FCC unit. This catalyst which contained no platinum had beenregenerated and then used to crack the same gas oil feedstock as inExample 1 under the same conditions.

The variously blended coked catalysts were regenerated under the sameconditions as in Example 2. The results were as follows:

    ______________________________________                                        Pt-Containing                                                                 Catalyst  Estimated                                                           in Blend, Pt in      CO.sub.2 CO                                              % by wt.  Blend, ppm % mol    % mol  CO.sub.2 /CO                             ______________________________________                                        0         0          5.7      5.0    1.1                                      1         0.01       4.6      2.4    1.8                                      2         0.02       4.8      2.4    1.9                                      4         0.04       4.4      2.3    1.9                                      20        0.20       6.7      0.6    11                                       50        0.50       6.1      0.68   9.0                                      100       1.0        8.1      1.3    6.2                                      ______________________________________                                    

This experiment indicates that even at concentrations as low as 0.01 ppmof added metal component, the CO₂ /CO ratio is increased duringregeneration.

The catalyst with added metal component may even contain an amount ofmetal component greater than that of the ultimate cracking catalystmixture, such as, for example, but not necessarily, 100 ppm, providedthat either in the use of the catalyst for cracking or in theregeneration of used catalyst it is blended with cracking catalystcontaining less or no metal component at sufficient concentrations toreduce the total added metal component to a concentration below 100 ppm.

It may thus be seen from the results of the cracking operations andsubsequent regeneration data that the catalysts of this invention arejust as effective in hydrocarbon conversion as conventional crackingcatalysts. However, in the regeneration step, the CO₂ /CO effluentratios are extraordinarily higher than catalysts without the added metalcomponent. The type of catalyst, feedstock or manner of introducing thenew component does not destroy the effectiveness in regenerationefficiency.

EXAMPLE 12

This example demonstrates that Pt is an effective CO oxidative agentwhen it is incorporated in a hydrous composite of all the gel componentsprior to spray drying.

A cracking catalyst incorporating 5 ppm of Pt with 15% rare earthzeolite Y in a silica-alumina clay matrix (60% SiO₂ -15% Al₂ O₃ -25%clay) was prepared as follows:

581.4 grams of WP grade Georgia kaolin were added to 45.2 lb (5.4gallons) of deionized water and the whole was mixed thoroughly. 4167grams Q-brand sodium silicate (1200 gms SiO₂) were added slowly to thewater-clay slurry, such that the clay was uniformly dispersed and coatedwith the sodium silicate. The mixture was heated to 120° F. and 216.1 mlconcentrated (96.9%) sulfuric acid was added at a uniform rate over aperiod of 25 min. while mixing. The whole mixture was then held at 120°F. for one hour while mixing, then allowed to cool to ambienttemperature. A solution of 1744.2 grams aluminum sulfate (500 gms Al₂O₃) dissolved in 6977 ml deionized water was added slowly to the mixturewhile stirring. The resulting mixture, which had a pH of 3.3, wastreated with 1150 ml of conc. ammonium hydroxide (29.8% NH₃) whilestirring, in order to precipitate the alumina on the silica gel. Themixture was then acidified with 93 ml concentrated sulfuric acid (95.9%)to a pH of 4.6.

294.2 gms of REY (68% of the sodium content had been replaced with rareearth cations), which had previously been calcined at about 1200° F. forabout 10 min., were dispersed in 883 ml deionized water in a Waringblender (the REY had the following composition: SiO₂ =57.9%; Al₂ O₃=19.0% RE₂ O₃ =15.4%; Na₂ O=3.6%). The zeolite slurry was added to thesilica-alumina-clay mixture while mixing. The zeolite-matrix slurry wasfiltered on a Buchner funnel and the filter cake reslurried withdeionized water to a total weight of 55 lbs, 230 gms ammonium sulfateadded, and the whole mixture stirred for 30 minutes. The compositehydrogel was then washed by filtering, reslurrying the filter cake withdeionized water to a total weight of 80 lbs and refiltering. Thiswashing procedure was performed three times. After the final filtration,the filter cake was reslurried to a total weight of 51 lbs withdeionized water; the pH of the final slurry was 4.5.

To the final slurry of the catalyst composite 5.7 mil of a solutioncontaining 2 mg Pt/ml as Pt (NH₃)₄ Cl₂ was added (a total of 11.4 mgPt). The mixture was homogenized and spray dried (inlet gas to spraydrier about 700° F. and outlet gas about 350° F.) to producemicrospheres of from about 1 to 140 microns in diameter, with an averagepartical size of 79 microns. A sample of the product analyzed asfollows: Na=0.39%, RE₂ O₃ =1.82%, Al₂ O₃ =25.0%.

The catalyst was steam treated and tested for cracking activity andselectivity as previously described. The oxidation activity wasdetermined by passing air (215° /min) through a fluidized bed of 10 gmsof a blend of coked and uncoked steamed catalyst containing a total of0.65% carbon at 1340° F. Analyses of the effluent gas for CO and CO₂gave a CO₂ /CO ratio of 2.9, substantially higher than would beanticipated for the same catalyst without platinum.

EXAMPLES 13-18

Platinum was incorporated in fresh samples of commercial catalystsproduced by the Filtrol Corporation. Filtrol 75-F, HS-7 and HS-10 wereimpregnated with aqueous solutions containing sufficient [Pt(NH₃)₄ ] Cl₂to give 5 ppm Pt in the finished catalyst. The amount of solution usedwas just sufficient to fill the pores of the catalyst, so that Ptretention was quantitative. In an additional preparation, theimpregnating solution contained both [Pt(NH₃)₄ ]Cl₂ and rare earthchloride hexahydrate sufficient to produce 5 ppm Pt and 3.0% RE₂ O₃ inthe finished catalyst. All the preparations were dried in air at 250°F., then mildly steam treated for 4 hours - 1400° F. - 0 psig in 100%steam in a fluidized bed.

Cracking activity and selectivity were tested by cracking a wide-cutMid-Continent gas oil over the steamed catalysts at 920° F., 3 C/O, 8.3WHSV in a fixed fluidized bed. The results of these tests showed thatthe presence of Pt produced no significant effect on activity orselectivity; in particular, Pt had a negligible effect on hydrogenfactor (see attached tables).

Oxidation activity was tested by blending the coked catalysts from thecracking test to 0.65% carbon with uncoked steamed catalysts, thenpassing a stream of air (215 cc/min) through a fluidized bed of 2 gms ofthe blended coked catalyst at 1190° F. The effluent gas was analyzed forCO and CO₂, activity being measured by the CO₂ /CO ratio. The results(attached tables) show very high oxidation activities for thePt-Containing catalysts.

    ______________________________________                                        Effect of Platinum on Filtrol 75-F                                            Example        13     14       15                                                                   Base +   Base + 5 ppm Pt                                               Base   5 ppm Pt and 3% wt RE.sub.2 O.sub.3                     ______________________________________                                        Treatment: Hours                                                                             4.0    4.0      4.0                                              : Temp., ° F.                                                                       1400   1400     1400                                             : % Steam    100    100      100                                            Conversion, % Vol                                                                            80.3   76.1     79.9                                           C.sub.5 + Gasoline, % Vol                                                                    66.7   63.5     66.1                                           Total C.sub.4, % Vol                                                                         15.8   14.5     15.5                                           Dry Gas, % Wt. 7.0    6.3      6.9                                            Coke, % Wt.    3.57   3.88     3.91                                           Hydrogen Factor                                                                              30     39       36                                             Recovery, % Wt 96.5   97.0     96.7                                           Oxidation Activity (1190 ° F., 2 gm Sample)                            CO.sub.2 /CO . 0.9    83       150                                            Relative CO.sub.2 /CO                                                                        1.0    92       167                                            ______________________________________                                        Effect of Platinum on Filtrol HS-7 and HS-10                                  Example        16     17       18                                                                   HS-7 +   HS-10 +                                                       HS-7   5 ppm Pt 5 ppm Pt                                       ______________________________________                                        Treatment: Hours                                                                             4.0    4.0      4.0                                              : Temp., ° F.                                                                       1400   1400     1400                                             : % Steam    100    100      100                                            Conversion, % Vol                                                                            81.6   84.4     80.3                                           C.sub.5 + Gasoline, % Vol                                                                    66.4   66.2     65.4                                           Total C.sub.4, % Vol                                                                         18.9   18.5     17.1                                           Dry Gas, % Wt  7.8    8.1      7.4                                            Coke, % Wt     4.44   5.55     4.17                                           Hydrogen Factor                                                                              35     37       45                                             Recovery, % Wt 95.9   97.2     96.3                                           Oxidation Activity (1190 ° F., 2 gm Sample)                            CO.sub.2 /CO   1.7    12       119                                            Relative CO.sub.2 /CO                                                                        1.0    7        70                                             ______________________________________                                    

EXAMPLES 19-31

Following is the preparation of a fluid cracking catalyst which servedas the base and for the preparation of the other examples of thisseries:

15% rare earth zeolite Y (REY) in silica-zirconia-alumina-clay matrix57.4% SiO₂, 2% ZrO₂, 0.6 Al₂ O₃, 40% clay.

1860.4 Grams of WP grade Georgia kaolin were added to 86.4 pounds (10.3gallons) of deionized water and the whole was mixed thoroughly. 7972.9Grams of Q-brand, sodium silicate (containing 2310 grams SiO₂) wereadded to the water-clay slurry. The sodium silicate was added slowlyover a period of thirty minutes while mixing. The clay was uniformlydispersed and coated with sodium silicate. The whole was heated to 120°F. and then 408.8 milliliters of aqueous sulfuric acid (97% wt H₂ SO₄)were added at a uniform rate over a period of one hour while mixing. Thewhole was then held at 120° F. for one hour. 139.5 Grams of aluminumsulfate in 560 milliliters of deionized water were added at uniform rateover a 1/2 hour period while mixing. To 178 grams of TAM sodiumzirconium silicate (Na₂ ZrSiO₅ : 24-26% Na₂ O; 46-49% Zr; 22-24% SiO₂)in 1730 milliliters deionized water were added 115 milliliters ofsulfuric acid (97% wt H₂ SO₄). This resulting slurry was then added tothe clay-silicate gel at uniform rate over a 1/2 hour period whilemixing. While agitating, additional sulfuric acid (97% wt H₂ SO₄) wasadded over the next 1/2 hour to lower the pH to 4.5. 726.7 Grams of REY(68% exchanged; i.e., 68% of the sodium content had been replaced withrare earth cations), which previously had been calcined at about 1200°F. for about 10 minutes, were slurried by dispersion in a Waring blenderin 2180 milliliters of deionized water. (The REY had the followingcomposition: Al₂ O₃ =19.0%; SiO₂ =57.9%; (RE)₂ O₃ =15.4%; Na₂ O=3.6%.)This slurry was added to the foregoing silica-zirconia-alumina-clayslurry while mixing. The blend was homogenized and then spray dried(inlet gas to spray drier about 700° F. and outlet gases about 350° F.)to produce microspheres of from about 1 to 140 microns in diameter, withan average particle size of about 62 microns.

The spray dried particles were then slurried with deionized water,decanted, and exchanged in a column with 40 gallons of a 5% aqueousammonium sulfate solution to remove sodium. Thereafter the particleswere washed with the water until the effluent was free of sulfate ions.The product was then dried in an oven at 250° F.

A sample of the product analyzed as follows:

    ______________________________________                                                    Wt percent                                                        ______________________________________                                               Na     0.05                                                                   (RE).sub.2 O.sub.3                                                                   1.95                                                                   NH.sub.3                                                                             0.64                                                            ______________________________________                                    

Platinum-group metals were incorporated by impregnating the dried solidbase catalyst with aqueous solutions containing the appropriatequantities of metal salts. The volume of impregnating solution wassufficient to just fill the pores of the catalyst, so that metalretention was quantitative. The particular salts were [Pt(NH₃)₄ ]Cl₂,[Pd(NH₃)₄ ]Cl₂, [Ir(NH₃)₅ Cl] Cl₂, [Rh(NH₃)₅ Cl]Cl₂, [Os(NH₃)₆ ]I₃, and[Ru(NH₃)₅ Cl]Cl₂.

Each catalyst was steamed in a fluidized bed for 4 hours at 1400° F. at0 psig with 100% steam, after being heated to 1400° F. in a stream ofnitrogen. The cracking activity and selectivity was tested by using thesteamed catalysts to crack a wide-cut Mid-Continent gas oil (29.2°API)in a fixed fluidized bed at 920° F., 3 C/O, 8.3 WHSV. The oxidationactivities were determined by blending the coked catalyst from thecracking test with fresh steamed catalyst to 0.65% wt carbon, passing astream of air at 215 cc/min through a fluidized bed of 4 gms of theblend at 1240° F. until all the carbon had been removed. The effluentgas was analyzed for CO and CO₂, the oxidation activity beingrepresented as the CO₂ /CO ratio (mole/mole).

The catalysts prepared, along with the data derived from the crackingand oxidation tests, are given in the following tables.

The cracking activity and selectivity data show that addition of up to10 ppm of any platinum group metal results in little or no decline inselectivity. Even at 50 ppm Pt, the hydrogen factor (100×moles H₂ /molesC₁ +C₂), a sensitive measure of metal poisoning, has increased from 13to only 40; many commercially acceptable cracking catalysts give similarhydrogen factors without an oxidation promoter.

Each catalyst shows a significant oxidation activity, although thedifferent metals have different activities. The activities are comparedin FIG. 3 (log-log plot). The approximate relative activities are:

    Ir≧Pt>Pd=Rh≧Ru>OS

    __________________________________________________________________________    Example        19 20 21 22 23   24 25 26 27 28 29 30 31                       Promoter       Base                                                                             Pt Pt Pt Pt   Pd Pd Ir Ir Rh Rh Os Ru                       __________________________________________________________________________    Promoter Content, ppm                                                                        .0 .5 5.0                                                                              10.0                                                                             50.0 2.0                                                                              10.0                                                                             2.0                                                                              5.0                                                                              5.0                                                                              10.0                                                                             5.0                                                                              5.0                      Cracking Test.sup.(1)                                                          Conversion, % Vol                                                                           79.8                                                                             78.3                                                                             76.6                                                                             75.5                                                                             76.9 79.2                                                                             77.7                                                                             78.0                                                                             76.2                                                                             76.7                                                                             79.3                                                                             74.7                                                                             79.2                      C.sub.5 + Gasoline, % Vol                                                                   68.8                                                                             64.8                                                                             64.9                                                                             62.2                                                                             64.2 66.0                                                                             65.8                                                                             65.6                                                                             63.1                                                                             64.5                                                                             65.5                                                                             61.3                                                                             67.2                      Total Butanes, % Vol                                                                        14.5                                                                             15.8                                                                             15.3                                                                             16.4                                                                             15.2 15.9                                                                             15.1                                                                             14.5                                                                             15.9                                                                             15.3                                                                             15.8                                                                             15.1                                                                             15.7                      Dry Gas, % Wt 6.7                                                                              7.0                                                                              6.5                                                                              6.8                                                                              6.6  7.1                                                                              6.4                                                                              6.4                                                                              6.5                                                                              6.6                                                                              6.9                                                                              7.3                                                                              6.1                       Coke, % Wt    2.8                                                                              3.4                                                                              2.7                                                                              3.1                                                                              3.3  3.0                                                                              2.7                                                                              3.3                                                                              3.3                                                                              2.8                                                                              3.4                                                                              2.7                                                                              2.8                       Hydrogen Factor.sup.(2)                                                                     13 17 22 26 40   17 18 15 19 13 13 15 13                       Oxidation Activity.sup.(3)                                                     CO.sub.2 /CO at 1240° F.                                                             0.77                                                                             1.8                                                                              43 49 1000 1.5                                                                              36 12 43 11 26 2.2                                                                              8.6                       Relative CO.sub.2 /CO Activity                                                              1.0                                                                              2.4                                                                              56 64 1304 1.9                                                                              47 16 57 15 34 2.8                                                                              11                       __________________________________________________________________________     .sup.(1) Fixed fluidized bed, WCMCGO, 8.3 WHSV, 3 C/O, 920° F.         .sup.(2) Moles H.sub.2 /Moles C.sub.1 +C.sub.2 × 100                    .sup.(3) 1240° F., 215 cc air/min, 4 g catalystcoked catalyst from     cracking test was blended with fresh steamed catalyst to give 0.65% wt C      on total sample                                                          

EXAMPLES 32-45 Platinum - Group and Transition Metals Incorporated onFresh DHZ-15

A commercial cracking catalyst, DHZ-15, manufactured by the DavisonChemical Division of W. R. Grace & Co., was impregnated with aqueoussolutions of Pt(HN₃)₄ Cl₂, Cr(NO₃)₃.6 H₂ O, MnCl₂.4H₂ O and Ni(NO₃).4 H₂O to the levels listed in the following table. The impregnating solutionvolume was sufficient to just fill the pore of the catalyst, so thatmetal retention was quantitative. The catalysts were steam treated,tested for cracking activity and selectivity, and oxidation activity asdescribed in Examples 19-31.

Incorporation of Pt to 1, 5 and 10 ppm shows very high oxidationactivity; cracking activity and selectivity show no degradation.

At a Cr level of 10,000 ppm (1% wt Cr), a severe loss in activity andsome loss in selectivity have occured, while only a minor increase inoxidation activity is observed, particularly in comparison to Pt (evenat 1 ppm). A similar result is obtained with Mn, where substantially nooxidation activity is evident even at 10,000 ppm. Incorporation of Mnhas, however, resulted in major losses in cracking activity.

Incorporation of nickel results in substantially no increase inoxidation activity, but results in serious losses in crackingselectivity, particularly with respect to increased coke yields andhydrogen factor.

                                      TABLE                                       __________________________________________________________________________    Example        32 33 34  35 36 37  38 39 40  41  42 43  44 45                 Promoter       Base                                                                             Pt Pt  Pt Pt Pt  Pt Cr Cr  Cr  Ni Ni  Mn Mn                 __________________________________________________________________________    Promoter Content, ppm                                                                        .0 .2 .4  .6 1.0                                                                              5.0 10.0                                                                             500                                                                              2,000                                                                             10,000                                                                            100                                                                              1,000                                                                             5,000                                                                            10,000             Cracking Test                                                                  Conversion, % Vol                                                                           71.8                                                                             74.2                                                                             73.9                                                                              75.2                                                                             75.8                                                                             71.0                                                                              77.0                                                                             74.8                                                                             77.6                                                                              60.8                                                                              73.9                                                                             76.5                                                                              67.4                                                                             56.4                C.sub.5 + Gasoline, % Vol                                                                   58.7                                                                             56.6                                                                             56.8                                                                              57.0                                                                             61.9                                                                             60.6                                                                              62.2                                                                             61.2                                                                             62.1                                                                              49.9                                                                              58.8                                                                             58.2                                                                              55.6                                                                             48.4                Total Butanes, % Vol                                                                        15.2                                                                             16.8                                                                             16.4                                                                              17.8                                                                             16.5                                                                             13.2                                                                              17.0                                                                             15.6                                                                             16.6                                                                              12.0                                                                              15.5                                                                             16.5                                                                              13.4                                                                             10.5                Dry Gas, % Wt 6.4                                                                              8.0                                                                              7.8 8.1                                                                              6.9                                                                              6.2 7.2                                                                              6.8                                                                              7.3 5.3 6.7                                                                              7.8 6.0                                                                              4.9                 Coke, % Wt    3.2                                                                              4.4                                                                              4.3 4.6                                                                              3.3                                                                              3.0 3.4                                                                              3.3                                                                              3.6 3.0 3.8                                                                              5.7 2.9                                                                              2.2                 Hydrogen Factor                                                                             26 22 22  23 27 23  30 23 21  23  45 142 23 23                 Oxidation Activity                                                             CO.sub.2 /CO at 1240° F.                                                             1.7                                                                              2.1                                                                              2.8 3.4                                                                              11 80  172                                                                              1.8                                                                              1.5 3.8 2.0                                                                              1.9 0.9                                                                              1.8                 Relative CO.sub.2 /CO Activity                                                              1.0                                                                              1.3                                                                              1.67                                                                              2.1                                                                              6.7                                                                              48  103                                                                              1.1                                                                              0.9 2.3 1.2                                                                              1.1 0.5                                                                              1.1                __________________________________________________________________________

EXAMPLES 46 and 47

As has been stated, the oxidation promoters of this invention are veryeffective for substantially complete conversion of CO to CO₂ in FCCregenerators. But, they can also be used to advantage in applicationswhere only partial conversion of CO is desired, as for example, in unitswhich are temperature limited by their materials of construction. Thesubstantial value of operating in a partial CO conversion mode isillustrated by these examples, which demonstrate the product yieldbenefits obtained in an active commercial test.

The test (Example 46) was made in an FCC unit of the Swirl regeneratortype, corresponding to FIGS. 1, 2 of the Drawings, which had beenoperating with Pt promoted DHZ-15 catalyst manufactured by the DavisonDivision of W. R. Grace & Company. The test run (Example 46) was made,after adding as makeup 66.8 tons of DHZ-15 promoted with 0.14 ppm Pt forover a period of 8 days, followed by 39.6 tons of DHZ-15 promoted with0.4 ppm Pt over the next 6 days, followed by 37.7 tons of DHZ-15promoted with 0.6 ppm over the next 7 days, and 21.6 tons of DHZ-15promoted with 0.8 ppm over the next 5 days. At this point, the amount ofnickel in the total catalyst inventory was about 190 ppm and the amountof vanadium was about 240 ppm. Platinum was 0.14 ppm, by calculation.

A second test run (Example 47) was made in the same FCC unit afterfurther addition of 42.2 tons of DHZ-15 promoted with 0.8 ppm Pt over aperiod of 7 days, followed by 21.3 tons of DHZ-15 promoted with 2 ppm Ptover the next 3 days. The platinum content was 0.31 ppm, by calculation.

Example 46 involves a low level of catalytic conversion of CO. Example47 test, which was made when the unit contained catalyst with a higherlevel of oxidation activity as indicated by the CO₂ /CO ratio in theflue gas, showed a substantial increase in conversion, a reduction incoke yield, an increase in gasoline yield and a reduction in carbon onregenerated catalyst even though this unit was still operated with onlypartial catalytic conversion of CO.

The results are shown in the following table.

                  TABLE                                                           ______________________________________                                                             Example                                                                              Example                                                                45     47                                                ______________________________________                                        Fresh Feed Rate, B/D   42,000   42,300                                        Coker in Feed, % Vol   23.9     24.7                                          Fresh Feed Gravity, ° API                                                                     22.5     22.8                                          Reactor Temp., ° F.                                                                           978      981                                           Avg. Regenerator Dense Bed Temp. ° F.                                                         1168     1228                                          Carbon on Regen. Catalyst, % Wt.                                                                     0.36     0.17                                          Flue Gas CO.sub.2 /CO Ratio                                                                          1.2      1.7                                           Conversion, % vol F.F. 66.2     69.4                                          Product Yields                                                                C.sub.2 and Lighter, F.O.E./B.                                                                       0.064    0.070                                         C.sub.3     % vol F.F.                                                                              3.5           3.9                                       C.sub.3 =   "         6.4           7.1                                       iC.sub.4    "         4.1           4.7                                       nC.sub.4    "         1.5           1.7                                       C.sub.4     "         7.5           7.9                                       C.sub.5 + Gasoline                                                                        "         45.3          47.3                                      Light cycle oil                                                                           "         28.5          25.5                                      Clarified Slurry oil                                                                      "         5.3           5.1                                       Coke,       % wt F.F. 6.7           6.4                                       ______________________________________                                    

The incremental yield of gasoline of 2% obtained in Example 47, comparedto Example 46, calculates a projected increase in production of about15,000,000 gallons per year for this unit alone. The unit could not havebeen operated to obtain these benefits without the use of the catalystof this invention.

It will also be seen that addition of platinum promoted catalyst to asystem which already contained CO promoter (Ni, V) did not, as might beexpected, result in loss of liquid yield until the catalyst circulationwas so far reduced that catalyst to oil ratio became controlling andcaused loss of gasoline production.

What is claimed is:
 1. A method for preparing, in situ, an inventorycomprising a carbon monoxide oxidation promoting metal and a crackingcatalyst for use in a fluid catalytic cracking process fornon-hydrogenative cracking of hydrocarbons, which cracking processcomprises cofeeding active hot solid cracking catalyst and crackablehydrocarbon feed to a cracking zone; cracking said feed to lighterhydrocarbons while depositing coke on said catalyst; disengaging saidcoked catalyst from said lighter hydrocarbon products; passing saidcoked catalyst to a regeneration zone; passing an oxygen containing gasupwardly through said regeneration zone and at sufficient velocity tofluidize said catalyst contained therein, whereby maintaining therein afluidized bed of catalyst having an ascending temperature profile;retaining said catalyst in said regeneration zone at a temperature andfor a time sufficient to burn coke off said catalyst, heat andreactivate such, and produce a flue gas comprising carbon oxides; andreturning said reactivated, heated catalyst to said cracking zone; saidmethod comprising adding, during said process into proximity to saidcracking catalyst, an amount of a platinum group metal as a decomposablecompound thereof, said amount being effective to increase thetemperature of said fluidized bed in said regeneration zone andineffective to substantially disadvantageously increase the productionof coke in said cracking zone, thereby forming said inventory comprisingsaid promoter metal in a proportion of 0.1 to 100 parts per millionbased on total catalyst.
 2. The method described in claim 1 wherein saidhot solid cracking catalyst comprises a crystalline aluminosilicatezeolite.
 3. The method described in claim 1 wherein the platinum groupmetal is platinum and the amount added is from 0.1 to 10 parts permillion parts of said hot solid cracking catalyst.
 4. The methoddescribed in claim 1 wherein said platinum group metal is added as aconcentrate deposited on cracking catalyst, said addition being made tohot solid cracking catalyst containing less or no platinum group metalcomponent.
 5. The method described in claim 2 wherein said platinumgroup metal is added as a concentrate deposited on cracking catalyst. 6.A method for preparing, in situ, an inventory comprising a carbonmonoxide oxidation promoting metal and a cracking catalyst for use in afluid catalytic cracking process for non-hydrogenative cracking ofhydrocarbons, which cracking process comprises cofeeding active hotsolid cracking catalyst and crackable hydrocarbon feed to a crackingzone; cracking said feed to lighter hydrocarbons while depositing cokeon said catalyst; disengaging said coked catalyst from said lighterhydrocarbon products; passing said coked catalyst to a regenerationzone; passing an oxygen containing gas upwardly through saidregeneration zone and at sufficient velocity to fluidize said catalystcontained therein, whereby sustaining therein a fluidized bed ofcatalyst having an ascending temperature profile; retaining saidcatalyst in said regeneration zone at a temperature and for a timesufficient to burn coke off said catalyst, heat and reactivate such, andproduce a flue gas comprising carbon oxides; and returning saidreactivated, heated catalyst to said cracking zone; said methodcomprising adding, during said process into proximity to said crackingcatalyst, an amount of a platinum group metal as a decomposable compoundthereof, said amount being effective to catalytically combust carbonmonoxide in said fluidized bed in said regeneration zone and ineffectiveto substantially disadvantageously increase the production of coke insaid cracking zone, thereby forming said inventory comprising saidpromoter metal in an amount less than 100 parts per million based ontotal catalyst.
 7. The method described in claim 6 wherein said hotsolid cracking catalyst comprises a crystalline aluminosilicate zeolite.8. The method described in claim 6 wherein the platinum group metal isplatinum and the amount added is from 0.1 to 10 parts per million partsof said hot solid cracking catalyst.
 9. The method described in claim 6wherein said platinum group metal is added as a concentrate deposited oncracking catalyst, said addition being made to hot solid crackingcatalyst containing less or no platinum group metal component.
 10. Themethod described in claim 7 wherein said platinum group metal is addedas a concentrate deposited on cracking catalyst.